1. Field of the Invention
The present invention relates to a method of handling electronic component chips and a combination of electronic component chip holders which are advantageously employed for carrying out the method.
2. Description of the Background Art
FIG. 10 is a perspective view showing an exemplary electronic component chip 1, to which the present invention can be applied. The electronic component chip 1 may be a capacitor chip such as a multilayer ceramic capacitor, a resistor chip, or an inductor chip, for example.
The electronic component chip 1 has first and second end surfaces 2 and 3, which are opposite to each other. A first end portion of the electronic component chip 1 including the first end surface 2 is provided with an external electrode 4, while a second end portion including the second end surface 3 is provided with another external electrode 5. Throughout the specification, the term "electronic component chip" includes a finished electronic component chip which is already provided with the external electrodes 4 and 5, as well as a semifinished electronic component chip which is not yet provided with the external electrode 4 and/or 5.
FIG. 11 shows an electronic component chip holder 6, which has generally been employed for forming external electrodes 4 and 5 on such electronic component chips 1. Such a holder 6 is disclosed in U.S. Pat. Nos. 4,395,184 and 4,381,321.
The holder 6 is in the form of a plate as a whole, and provided with a number of receiving portions 7, which are defined by through holes, for receiving the electronic component chips 1, in order to efficiently carry out a step of forming external electrodes.
FIG. 12 shows a section of the holder 6. This holder 6 comprises cores 8 which are covered with an elastic member 9, and the aforementioned receiving portions 7 are defined by through holes which are formed to pass through the elastic member 9. Thus, the electronic component chips 1 inserted in the receiving portions 7 are held by elasticity of the elastic member 9.
In order to form the external electrodes 4 and 5 on the electronic component chips 1, the following operation is carried out:
First, the electronic component chips 1 are inserted in the receiving portions 7 of the holder 6, so that a plurality of electronic component chips 1 are held by the holder 6 as shown in FIG. 12. An orientation device and pushers, which are not shown in the figure, can be employed for inserting the electronic component chips 1 in the receiving portions 7.
On the other hand, electrode paste 11 is applied onto a surface plate 10 in a prescribed thickness.
Then, the holder 6 is moved toward the surface plate 10 as shown by arrow 12, to dip the electronic component chips 1 in the electrode paste 11. Thus, the external electrodes 4 are formed on first end portions of the electronic component chips 1 including the first end surfaces 2, for example.
The external electrodes 4 formed by the electrode paste 11 are dried.
The electronic component chips 1 are extruded by pushers toward an opposite surface of the holder 6 through the through holes defining the receiving portions 7, and held in a state exposing the second end portions including the second end surfaces 3.
A step substantially similar to that shown in FIG. 12 is carried out to form the other external electrodes 5.
While such a holder 6 is adapted to handle a number of miniature electronic component chips, recent development of miniaturization of electronic component chips sometimes leads to difficulty in employment of such a holder 6. Since the receiving portions 7 of the holder 6 must be reduced in inner diameter following reduction in size of the electronic component chips, it is difficult to manufacture the holder 6 itself. Further, pushers for inserting and transferring the electronic component chips in and from the receiving portions 7 of the holder 6 must have operating portions which are smaller in diameter than the receiving portions 7. Thus, the operating portions of the pushers are made so insufficient in strength that it is difficult to properly use the same. In addition, parts of the electronic component chips inserted in the receiving portions 7 are reduced in length, and hence it is difficult to hold the electronic component chips by the holder 6.
While the above description is made in relation to the step of forming external electrodes on the electronic component chips, a similar problem may also be caused in a step of performing processing other than formation of external electrodes on the electronic component chips.
On the other hand, Japanese Utility Model Laying-Open No. 62-140720 (1987) describes a holder for holding electronic component chips with adhesion, for measuring characteristics of the electronic component chips. This holder comprises an elastic member of silicone rubber, for example, having viscosity at least on its surface, to hold electronic component chips on the surface of the elastic member with adhesion. Terminals for measurement are brought into contact with the electronic component chips held in such a manner, to measure prescribed electric characteristics of the electronic component chips.